Telecom shelter cooling and control system

ABSTRACT

A system configured to provide cooling of electronic equipment in a shelter in combination with an air conditioning (A/C) system. The system includes one or more blowers for drawing air into the shelter, a damper arrangement for controlling air exhaust. The system further includes a DC powered controller coupled to the one or more blowers, the damper arrangement, and the A/C system. The controller is configured to receive at least a first analog input signal associated with a shelter-interior temperature, a second analog input signal associated with a shelter-exterior temperature, and a plurality of alarm input signals and to generate the one or more first control signals to control blower rotational speed, the second control signal to open/close the damper arrangement, and a third control signal to inhibit/activate the A/C system based on at least the first analog input signal, or the second analog input signal, or a plurality of alarm input signals, or a combination of these.

BACKGROUND OF THE INVENTION

The present invention relates generally to system cooling techniques. Inparticular, embodiments of the present invention provide a method andsystem for providing an alternate cooling to an outdoor shelter housingelectrical equipment. Merely by way of example, the invention has beenapplied to telecommunications shelters, but it would be recognized thatthe invention has a much broader range of applicability.

Telecommunication (telecom) shelters are typically constructed as anoutdoor facility in either steel or pre-cast concrete structure forhousing an electrical system. Physical dimensions for such shelters areabout 20 ft in length, 10 ft in width, 10 ft in height with an accessdoor and several access hatches for cable access. These shelters areusually attached to split system air-conditioning units for providingcooling for the electrical system therein. A conventional airconditioning (A/C) system associated with the shelter is typicallypowered from standard Alternating Current (AC) power supply and henceonly operates and provides cooling as long as there is AC poweravailable.

However, the electrical system within the telecom shelter usually needsto operate from a Direct Current (DC) voltage converted from the ACinput by one or more DC power supplies disposed inside the shelter. ThisDC voltage is typically +24 VDC or −48 VDC and there are typically banksof batteries provided in the shelter to store this DC Power. Thebatteries are installed so that the systems can operate during eventswhere the AC power is interrupted to the shelter. Cooling for outdoortelecom shelters is critical for proper operation of the electronicshoused therein. Typically the telecom equipment installed in theshelters has an over-temperature shutdown monitor built into theequipment. Thus, the time that the telecom systems can operate is notlimited by the battery life, but is limited by the time that the systemcan operate before it reaches the over-temperature shutdown thresholdwhen the A/C system for providing cooling to the shelter is no longerfunctioning. This time depends on the external ambient conditions but istypically quite short ( approx 20 minutes to 1 hour) for conventionaltelecom shelter. One potential solution is to use a DC to AC inverter inthe event of a standard AC power failure. However, this is considered tobe not practical, because it would require a very large battery storagecapability.

In conditions where a large amount of the telecom shelters lose power atthe same time (such as in a hurricane event), the telecom equipmentinstalled in the shelter is not available for subsequent rescue efforts.If cellular phone systems are used to communicate, 20 minutes is notenough time to restore power to so many systems. Due to a recent eventthat caused a sustained lack of communication (hurricane Katrina), thefederal regulations have been changed. Telecom shelters are now requiredto operate for 4-8 hours after loss of standard AC power.

Therefore, an alternate system and method for providing cooling to theoutdoor shelter of electrical equipment are desired.

BRIEF SUMMARY OF THE INVENTION

The present invention relates generally to system cooling techniques. Inparticular, embodiments of the present invention provide a method andsystem for providing an alternate cooling to an outdoor shelter withtelecom equipment installed therein.

Embodiments according to the invention lead to a system configured toprovide controlled cooling of electronic equipment in an outdoor shelterin combination with an air conditioning (A/C) system powered by AC powersupply. The electronic equipment is powered by a DC supply. The systemincludes one or more blowers configured to be mounted to the outdoorshelter to draw exterior air into the outdoor shelter. Additionally, thesystem includes a damper arrangement configured to be mounted at an airexhaust region of the outdoor shelter. Moreover, the system includes acontroller powered by the DC supply and coupled to the one or moreblowers, the damper arrangement, and the A/C system. The controller isconfigured to receive at least a first analog input signal associatedwith a shelter-interior temperature, a second analog input signalassociated with a shelter-exterior temperature, and a plurality of alarminput signals. The controller is further configured to generate the oneor more first control signals, the second control signal, and a thirdcontrol signal based on at least the first analog input signal, or thesecond analog input signal, or a plurality of alarm input signals, or acombination of thereof. In one embodiment, the one or more first controlsignals respectively control an on/off operating state of the one ormore blowers including rotational speeds of the one or more blowers. Thesecond control signal controls opening and closing of the damperarrangement in correspondence of the on/off operating state of the oneor more blowers. The third control signal inhibits/activates the A/Csystem.

In an alternative embodiment, the present invention leads to a systemfor providing alternative cooling, in addition to an air conditioning(A/C) system, to a cabinet housing electrical equipment. The systemincludes a blower subsystem including one or more blowers for drawingair into the cabinet. The system further includes a damper subsystemincluding a louver arrangement for controlling air exhaust.Additionally, the system includes a controller operated from a DCsupply. The controller includes a microprocessor having at least a firstanalog input, a second analog input, a plurality of alarm inputs, one ormore first control outputs, a second control output, and a third controloutput. The first analog input connects to a first thermistor to measurea first temperature inside the cabinet. The second analog input connectsto a second thermistor to measure a second temperature outside thecabinet. The third control output connects to the A/C system forinhibiting or re-activating the A/C system based on at least the firsttemperature and the second temperature. The one or more first controloutputs connect to the blower subsystem for respectively operating theone or more blowers based on at least the first temperature when the A/Csystem is inhibited or stopped for any reason. The second control outputconnects to the damper subsystem for opening/closing the louverarrangement when the one or more blowers are operating/stopped.

In another alternative embodiment, the present invention provides amethod for providing an alternative cooling in addition to an airconditioning (A/C) system to a cabinet housing electrical equipment. Themethod includes providing a cooling system to the cabinet. The coolingsystem includes a blower subsystem including one or more blowers fordrawing air into the cabinet and a damper subsystem including a louverarrangement for controlling air exhaust. Additionally, the coolingsystem includes a controller operated from a DC supply. The controllerincludes a microprocessor having at least a first analog input, a secondanalog input, a plurality of alarm inputs, one or more first controloutputs, a second control output, and a third control output. The methodfurther includes activating the controller by starting up power from theDC supply. Additionally, the method includes receiving informationassociated with an interior temperature from the first analog input andinformation associated with an exterior temperature from the secondanalog input and monitoring information associated with a general alarmand a plurality of specific alarms received through the plurality alarminputs. Moreover, the microprocessor processes information associatedwith the exterior temperature and information associated with a generalalarm and a plurality of specific alarms. If the exterior temperature islower than a predetermined value, or no general alarm or one of theplurality of specific alarms is triggered, the microprocessor processesinformation associated with the interior temperature.

If a first criterion based on information associated with the interiortemperature is satisfied, then the method includes a process ofinhibiting the A/C system through the third control output. The methodalso includes another process of operating each of the one or moreblowers, respectively through the one or more first control outputs, ata rotation speed depending on the information associated with theinterior temperature. The method further includes a process ofclosing/opening the louver arrangement through the second control outputwhen the rotation speed is/isn't zero.

If a second criterion based on information associated with the interiortemperature is satisfied, then the method includes a process ofactivating the A/C system in cooling mode through the third controloutput and a process of stopping the one or more blowers through the oneor more first control outputs.

If a third criterion based on information associated with the interiortemperature is satisfied, then the method includes a process ofactivating the A/C system in heating mode through the third controloutput and a process of stopping the one or more blowers through the oneor more first control outputs.

Many benefits are achieved by way of the present invention overconventional techniques. For example, embodiments of the presentinvention provide an alternate cooling system in place of conventionalair conditioning system, which can be used for cooling outdoor shelterhousing electrical equipment in the events where standard AC power isinterrupted or failed. Certain embodiments of the present inventionsignificantly reduces energy use and operation costs of thetelecommunication shelter. Some embodiments further provide sustainedoperation of the communication electronics within the shelter in theevent of a power failure during hurricane or earthquake. Under updatedfield application requirement for 4-8 hours after loss of power, theexiting telecom shelter can be kept for using with minimum amount ofmodification and installation of the direct air cooling system based onpresent invention. Further, some embodiments of the present inventionprovide additional cooling system redundancy for providing controlledcooling in response to various alarming situations. For example, in theevent of an excess hydrogen alarm event, the system according to anembodiment of the present invention also serves to accelerate exhaustingof the shelter. Or in the event of detecting fire-related smoke insidethe shelter, the system according to an embodiment of the presentinvention can has a function to starve the fire by closing the oxygensupply. Depending upon the embodiment, one or more of these benefits, aswell as other benefits, may be achieved. These and other benefits willbe described in more detail throughout the present specification andmore particularly below in conjunction with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a side view of a cooling systemaccording to an embodiment of the present invention;

FIG. 2 is a schematic diagram showing the top view of a cooling systemaccording to the embodiment of the present invention;

FIGS. 3A and 3B are simplified diagrams showing a blower subsystemincluding four blowers and a controller according to an embodiment ofthe present invention;

FIG. 4 is schematic diagram showing a telecom shelter with a direct aircooling system according to embodiments of present invention in additionto a traditional air conditioning system;

FIG. 5A is a controller functional block diagram according to anembodiment of the present invention;

FIG. 5B shows three-angle views of the controller built on a PC boardaccording to an embodiment of the present invention;

FIGS. 6A and 6B show a simplified flow chart outlining a method ofproviding controlled cooling for an outdoor shelter according to anembodiment of the present invention; and

FIGS. 7-11 each is a simplified flow chart showing a method forproviding controlled cooling for an outdoor shelter according to analternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates generally to system cooling techniques. Inparticular, embodiments of the present invention provide a method andsystem for providing an alternate cooling to an outdoor shelter housingelectrical equipment. Merely by way of example, the invention has beenapplied to a telecommunication shelter, but it would be recognized thatthe invention has a much broader range of applicability.

FIG. 1 is a schematic diagram showing a side view of a cooling systemaccording to an embodiment of the present invention. This diagram ismerely an illustration and should not limit the scope of the claimsherein. One of skilled in the art should recognize many alternatives,variations, and modifications. As shown in one implementation, a directair cooling system 100 is structured to be mounted on a position of ashelter door 200 (side view is shown). At least partially, the directair cooling system 100, or simply called the cooling system, includesone or more blowers 101 disposed at an interior side of the shelter door200 opposing a filter arrangement 103 at an exterior side of the shelterdoor 200. In one embodiment, the one or more blowers are fan traysstructured as two channels, each with two blowers. In particular, eachblower can be a DC powered radial blower. For example, in a specificimplementation a NMB 48V 225 mm radial blower can be used (NMB Part No.225R103 D0801). The filter arrangement 103 is configured to cover theair inlet region 102 of the one or more blowers 101 for the purpose ofremoving dust and moisture from the air as it is drawn into the shelterby the one or more blowers 101. As shown, the cooling system 100 isincorporated with a damper arrangement 105 including a plurality oflouver blades that are electrically operated to an open position orclose position to control the flow of air exhaust. Though the pluralityof louver blades are shown to be oriented in horizontal direction, theycan be implemented in other orientations. In one embodiment, the damperarrangement 105 is configured to be mounted at a location where air isexhausted from within the shelter. This location can be elsewhere on theshelter other than the same position where the one or more blowers 101are mounted. For example, a cable duct region can utilized forinstalling the damper arrangement 105.

Additionally, the cooling system 100 includes a microprocessor-basedcontroller 120 disposed within a same enclosure that houses the one ormore blowers 101. In certain embodiments, the controller 120 isconfigured to send one or more control signals to operate the one ormore blowers 101 when an existing air conditioning (A/C) system (notshown) for the shelter is optionally inhibited (by the same controller120) or stopped subjecting to power failure or other electrical ormechanical faults. In some embodiments, the controller 120 also isconfigured to send a control signal through connection 125 to the damperarrangement 105 to open or close the plurality of louver blades. In aspecific embodiment, the one or more blowers 101 are configured to drawin cool exterior air into the shelter for cooling the electricalequipment therein. Accordingly, the damper arrangement 105 is operatedto an open position to allow heated air to exhaust out of the shelterwhen the one or more blowers 101 are operating, and can be closed toseal the shelter when the one or more blowers are not operating. Inanother specific embodiment, the damper arrangement 105 can have aspring return feature that allows it to be open when DC power is on andautomatically closed when power is removed for any reason.

FIG. 2 is a schematic diagram showing a top view of the cooling system100 according to an embodiment of the present invention. This diagram ismerely an illustration and should not limit the scope of the claimsherein. One of skilled in the art should recognize many alternatives,variations, and modifications. As shown, the direct air cooling system100 mounted on the shelter door 200 is viewed from top of the doorlooking down. On the exterior side of the door, now a door handle 201can be seen. Similar to FIG. 1, the one or more blowers 101 and thefilter arrangement 103 are respectively disposed on interior side andexterior side of the shelter door 200.

In a specific embodiment, the controller 120 of the direct air coolingsystem 100 is coupled to one or more temperature measuring devices. Theone or more temperature measuring devices include at least a firstthermistor for measuring a shelter-interior temperature and a secondthermistor for measuring a shelter-exterior temperature. For example,though not explicitly shown in FIG. 1 or FIG. 2, the first thermistorcan be installed next to the one or more blowers 101 at the interiorside of the shelter door 200, and the second thermistor may be installedoutside the shelter door 200 near the filter arrangement 103.Correspondingly, the controller 120 is able to receive at least a firstanalog input signal indicative to the shelter-interior temperature and asecond analog input signal indicative to the shelter-exteriortemperature. The controller is configured to generate control outputsignals based on at least the first analog input signal and the secondanalog input signal for controlling the one or more blowers 101 as wellas the damper arrangement 105 with options of inhibiting/activating theA/C system. In one example, if the exterior temperature is too high(exceeding a predetermined value) then the direct air cooling system 100may be turned off while the A/C system can be activated to providingadequate cooling for the shelter in traditional manner.

In another specific embodiment, the controller 120 further is coupledwith a plurality of sensing devices disposed at various locations of theshelter (schematically shown in FIG. 4 below) and a plurality of alarmoutput devices disposed on-board (schematically shown in FIG. 5B below).Examples of the plurality of sensing devices includes a smoke sensor, ahydrogen sensor, a pressure sensor, one or more voltage sensors (e.g.,AC power monitoring module and DC supply voltage monitor), a pressuresensor, and others for detecting various environmental and operationalconditions. The controller 120 is configured to receive and process aplurality of alarm input signals from the plurality of sensing devicesand output a plurality of alarm output signals through the plurality ofalarm output devices. The plurality of alarm output devices includeon-board contact relays and alarm display devices. For example, Form Ccontact relay is used. In certain implementation, the alarm displaydevices include several LEDs which use light color, single color orbi-color, to indicate normal or certain alarm condition. In addition tothe analog input signals associated to the interior/exteriortemperature, the controller 120 also is configured to modify the controlsignals for the one or more blowers 101, the damper arrangement 105, andthe A/C system based on specific alarm input signal received.

FIGS. 3A and 3B are simplified diagrams showing a blower subsystemincluding four blowers and a controller according to an embodiment ofthe present invention. These diagrams are merely illustrations andshould not limit the scope of the claims herein. One of skilled in theart should recognize many alternatives, variations, and modifications.As shown, the blower subsystem 300 includes four blowers 101 installedwithin an enclosure made of a sheet metal structure 107. Each blower 101is disposed behind an air inlet region 102 facing exterior side when theblower system is mounted to a shelter. In one embodiment, the fourblowers 101 are powered by a DC supply (e.g., as shown in FIG. 4 below)and used to draw the cool exterior air into the shelter, taking out theheat generated from the operating telecom equipment through an exhaustregion. The DC supply for the blower subsystem can be the same DC supplyconventionally provided for the equipment within the shelter or aseparate DC supply. For example, the DC supply can be an AC-to-DCinverter, or a battery, a rechargeable battery, a fuel cell, or a solarcell, and others. In the event of a power failure, these blowers 101 cancontinue to operate normally from the battery back up system of the DCsupply, which allows the entire shelter to operate as long as there isenough power in the batteries.

In a specific embodiment, each blower 101 can be a DC powered radialblower. For example, in a specific implementation a NMB 48V 225 mmradial blower can be used (NMB Part No. 225R103 D0801). In one example,the four blowers 101 are configured into two channels, each channel hastwo blowers under closed-loop speed control by the controller 120. Thecontroller 120 can be seen in the blower subsystem 300 in FIG. 3B whereone side panel of the sheet metal structure 107 is removed. In aparticular implementation, the controller 120 uses a pulse widthmodulated (PWM) speed control signal to control blower rotation speed bymonitoring tachometer signals obtained from each radial blower inresponse to one or more speed control input signals. More detail about acontrol method of the direct air cooling system in combination with anexisting air conditioning system to provide cooling for the outdoortelecom shelter can be found in following paragraphs.

FIG. 4 is schematic diagram showing a telecom shelter with a direct aircooling system according to embodiments of present invention in additionto a traditional air conditioning system. This diagram is merely anillustration and should not limit the scope of the claims herein. One ofskilled in the art should recognize many alternatives, variations, andmodifications. As shown, in a perspective view a telecom shelter 401 isan outdoor structure with a length L, a width W, and a height H thathouses electric equipment for telecommunications. In one application,the electric equipment in the telecom shelter 401 comprises all userequipment and software needed for communication with a wirelesstelephone network. As shown, optionally an antenna 431 is disposed abovethe telecom shelter on a top part of a mast 430 for signal transmissionor reception. The shelter 401 itself can be made from a pre-castconcrete structure or from a steel structure. In one example, the lengthL is about 20 ft and the width and height each about 10 ft. In anotherexample, the shelter can be used for housing equipment for manyalternate applications other than telecommunication.

The telecom shelter 401 includes an access door 200 built on one side.In one embodiment, a direct air cooling system 100 is mounted on theaccess door 200 in a manner the same as one shown in FIG. 1 and FIG. 2,and a filter arrangement 103 is at least partially visible from exteriorside of the shelter door 200. The direct air cooling system 100 has ablower subsystem including one or more blowers disposed at the interiorside of the shelter door 200, which are not directly visible in FIG. 4.Of course, the blower subsystem of the direct air cooling system 100 canbe mounted on any other side or position of the shelter 401. On analternative side of the shelter 401, an existing air conditioning (A/C)system including two independent working units 411 and 413 have beeninstalled. The A/C system 411 and 413 are usually powered by standard ACpower supply connected to a power grid through a cable box 420. In oneembodiment, the telecom shelter 401 also includes an AC-DC inverter 425to transform the AC power into a nominal −48V standard DC power (with−36V to −60V range) which is normally used for operatingtelecommunication equipment within the telecom shelter 401. In anotherembodiment, the AC power can be transformed into a nominal +24V standardDC power (with 19V to 29V range) which can be used for operating varioustelecommunications equipment and the like. An electrical connection 115links the AC-DC inverter 425 to the direct air cooling system 100 todeliver DC power for its operation and control functions. In certainimplementation, a separate DC supply can be used for the direct aircooling system 100. For example, the DC supply can be a battery, arechargeable battery, a fuel cell, or a solar cell, and others.

Referring to FIG. 4 again, on a side of the telecom shelter 401 a dampersubsystem 105 can be mounted over an air outlet or exhaust region, whichis coupled to the blower subsystem (e.g., the blower subsystem 300 shownin FIG. 3A, including filter arrangement) through another electricalconnection 125. In another embodiment, the damper subsystem 105 ispowered by one of several on-board DC power supplies (e.g., a +24Vsupply shown in FIG. 5A below) built on a controller through DC-DCconverters from the DC supply mentioned above. As shown, the dampersubsystem 105 includes a plurality of louver blades that areelectrically actuated to open to allow air exhausting when the blowersof the direct air cooling system 100 is operating or to close to sealthe shelter 401 when the blowers of the direct air cooling system 100 isnot operating. Other types of damper arrangements other than horizontalorientated louvers can be implemented. One of skilled in the art shouldrecognize many alternatives, variations, and modifications. In oneexample, the damper subsystem 105 is configured to be mounted over acable duct in order to allow the field upgrade of the telecom shelterwithout affecting the structural integrity while providing a minimallyinvasive rework event. In a particular implementation, a wind drivenrain hood 106 is mounted on the exterior side of the damper subsystem105.

The direct air cooling system 100 described above is designed towithstand harsh outdoor environmental conditions. In particular, thedirect air cooling system, or simply the cooling system, should notsuffer damage when mounted to a shelter and exposed to temperatures inthe range of about −45 Deg C. to about +85 Deg C. The cooling systemitself should be operational within a temperature range between about−40 Deg C. and about +50 Deg C. Additionally, the system is designed towithstand certain external vibrations. For example, the cooling systemshould not suffer any damage and be able to continue operating when itis subjected to the following vibration conditions. 1) Random vibrationduring operating: for 20 minutes along all each of three axes sustainaxial vibration force with a vibration intensity of 0.0001 g²/Hz withina frequency range from 5 to 350 Hz and a vibration intensity droppedfrom its maximum in a rate of −6 dB/octave within a frequency range of350 to 500 Hz. 2) Random vibration for survival: for 20 minutes alongall each of three axes sustain axial vibration force with a vibrationintensity of 0.015 g²/Hz within a frequency range from 3 to 100 Hz and avibration intensity dropped from its maximum in a rate of −6 dB/octavewithin a frequency range of 100 to 137 Hz, and a vibration intensity of0.008 g²/Hz within a frequency range from 137 to 350 Hz and a vibrationintensity dropped from its maximum in a rate of −6 dB/octave within afrequency range of 350 to 500 Hz. 3) Swept sine vibration for survival:0.5 g acceleration (from 0 to peak) within a frequency variation from 3to 500 and to 3 Hz. The test is for resonant search along all three axeswith 15 minutes dwell at all resonances and with 1 octave/minute sweeprate. Furthermore, the cooling system should withstand certain shocktest. For example, the system should not suffer any damage whensubjected to the following test: a half sine shock test with durationless than 3 milliseconds and a speed difference of about 1.65 meters persecond. The shock test should be conducted minimum 3 times on each of 6faces of the system. Moreover, the cooling system is designed to meetregulatory requirement of UL/EN 60950. More detail about a controlmethod of the direct air cooling system using one or more DC operatedblowers in association with a damper arrangement to provide controlledcooling for the outdoor telecom shelter can be found in followingparagraphs.

FIG. 5A is a controller functional block diagram according to anembodiment of the present invention. This diagram is merely anillustration and should not limit the scope of the claims herein. One ofskilled in the art should recognize many alternatives, variations, andmodifications. As shown, the controller 500 includes a microprocessor501 operated by DC power delivered through a power input port 510. Thecontroller 500 is designed to monitor the external and internalenvironment of the telecom shelter and control one or more blowers ormotorized impellers to draw cold air from exterior to cool the interioroperating equipment. In one implementation of the invention, thecontroller 500 is the controller 120 installed with the direct aircooling system 100. The DC supply is in a range of −36 to −60 VDCnormally found for telecommunication equipment. Subsequently, the powerinput 510 to the controller 500 is first coupled through anElectromagnetic Compatibility (EMC) filter 520. Fuses included in theEMC filter 520 can be rated at about 20 Amps. The EMC filter 520 issupplement to a corresponding EMC filter fitted in each of the one ormore blowers. The EMC filter 520 can limit the conduction of controllernoise and motor noise to the system. In one example, the EMC filter 520is designed to provide sufficient attenuation to meet the CErequirements for most applications. In one embodiment, the EMC filterdesign is dependent on the type of motor used for the one or moreblowers and their installation locations. The design performance canonly be confirmed in the specific final application.

In one embodiment, the controller 500 includes function to monitor theDC supply voltage. In one example, the interface of the power input 510is via a connector J1 which has 5 pins J1-1 through J1-5 shown inTable 1. As shown, connector pins J1-1 and J1-2 a connected for 0 VReturn signal. Connector pin J1-3 is for chassis ground. Connector pinsJ1-4 and J1-5 are connected for −DC voltage supply. The connector can be¼ PCB mounted “Faston” Blade Terminals. For example, a power connectorwith AMP Part No 62409-1 can be used.

TABLE 1 Connector Ref Function Signal type J1-1 0 V A 0 V Return J1-2 0V A 0 V Return J1-3 Ground Chassis Ground J1-4 −Ve Supply −DC supplyJ1-5 −Ve supply −DC supply

Additionally, the controller 500 incorporates its own on-board DC powersupplies including a +24V supply 540, +10.5V supply, and a +5V supply530. The +24V power supply 540 is to generate the necessary power forthe smoke alarm, the hydrogen alarm and the operation of damperarrangement. The +10.5V supply is for generating the PWM speed controlsignals and for energizing relays. Another on-board +5V supply 530 isdirectly coupled to the microprocessor 501 via a connection 535 forlogic supply required by the microprocessor 501.

The microprocessor 501 is configured to directly couple with one or moreblowers through one or more blower output ports 550. In oneimplementation, the controller 500 is designed to control variable speedblowers and deliver DC power to up to four motorized impellers which arecontrolled in two channels of two blowers dependent on the profileinformation programmed into the microprocessor 501. Each blower output550 can be individually fused to prevent a single blower failure pullingthe whole system down. The DC voltage supplied to these blowers is thesame voltage supplied from the DC input 510 less any volt drop in theEMC filter 520. The interface associated with each of these bloweroutput ports between the microprocessor 501 and each of the blowers canbe via a 6-way connector. For example, 4 connectors, named as J2 throughJ5, are respectively used for four DC-driven radial blowers. Table 2shows an example of the pin layout for the connector J2 though J5. Forexample, a Molex Minifit Jnr Right angle PCB mounted connector (MolexPart No. 39-30-0060) can be used.

TABLE 2 Connector Ref Function Signal type (on Controller) Pin 1 NoConnection Pin 2 0 V Return +DC Supply to blowers Pin 3 Speed ControlPWM Logic Signal to blower Pin 4 Ground Chassis Ground connection Pin 5Tacho Logic Signal from blower Pin 6 −48 V Supply −DC Supply to blowers

Referring to FIG. 5A, the controller 500 includes two temperature sensorinputs 560 coupled to the microprocessor 501. Physically, each of thetwo temperature sensor inputs 560 is coupled to a thermistor to transferinformation about either a shelter-interior temperature or ashelter-exterior temperature to the microprocessor 501 via one of twointerface connectors J6 and J7. In particular, the controller 500continuously monitors an analog voltage input from the correspondingthermistor. If the analog voltage input represents a temperature of lessthan −43 Degrees of Centigrade, then the controller considers that thethermistor is short circuited. If the analog voltage input represents atemperature of +85 Degrees of Centigrade and above, the controller thenconsiders the thermistor to be open circuited. In either event, thecontroller 500 will trigger a thermistor alarm. Of course, the specificvalues of those temperature limits can be custom defined. The interfacebetween the thermistors 560 and the microprocessor 501 can be via afollowing connector pinout shown in Table 3. For example, each of the J6and J7 connector can be a 2 way Molex KK Type 2.54 mm pitch header withfriction lock connector (Molex Part No. 22-23-2021) can be used.

TABLE 3 Connector Ref Function Signal type (on Controller) Pin 1 Signalreturn Thermistor connection Pin 2 Signal out Logic +5 V

Referring again to FIG. 5A, the controller 500 also has several alarminput and control output ports 570 coupled to the microprocessor 501.The alarm input ports are used for coupling with a plurality of sensingdevices and the control output ports include at least one output forcontrolling a damper arrangement and another output for inhibit an A/Csystem. Example of the plurality of sensing devices used here includes asmoke sensor, a hydrogen sensor, and one or more AC power monitoringmodules. Correspondingly, in certain alarming condition one or morealarm input signals can be generated by one or more sensing devices andsent via the alarm input ports to the microprocessor 501. In oneimplementation, the alarm input port is configured to be an isolatedcontact relay which is closed when alarming (e.g., when detecting smokeor excess hydrogen in shelter). A +24V on-board DC supply 540 is used toprovide DC power through one output port for the smoke sensor, thehydrogen sensor, and a damper actuator. This output is capable ofdelivering a maximum power of 450 mA at 24V and is protected againstshort circuit by a PTC (Polyswitch automatically resetting fuseelement). A +24V switched output control signal can be provided throughanother output port to the damper arrangement for operating the exhaustdamper to open or close. The power associated with the damper switchingcontrol is about 350 mA. The AC power monitoring module is used by thesystem to monitor the AC power delivered to an air conditioning (A/C)system originally associated with the telecom shelter. For example, theAC power monitoring module monitors power outputs from two circuitbreakers supplying AC power to two A/C units. Two input signalsassociated with the AC power monitoring module are generated fromcorresponding two alarm input ports with isolated contacts. Eachisolated contact has a relay coil energized to have open contact innormal mode and closed contact when alarming (detecting AC power supplyfailure/interruption). Moreover, the controller 500 includes a Form Ccontact output for inhibiting/activating the A/C system. The relay coilassociated with this output port is configured to be energized when theA/C system is inhibited or disabled. As a result, the interfaceassociated with these alarm input and control output ports is via a 10way connector. For example, connector J8 can be a Molex connector of KKtype 2.54 mm pitch header with friction lock (Molex Part No.22-23-2101). Table 4 shows the connector pinout.

TABLE 4 Connector Ref Function Signal type J8-1 +24 V Power Supply J8-2Damper +24 V Damper Control J8-3 Smoke Alarm Alarm contact input J8-4Hydrogen Alarm Alarm contact input J8-5 AC Supply 1 Alarm contact inputJ8-6 AC Supply 2 Alarm contact input J8-7 0 V Power/logic 0 V J8-8 ACinhibit Common Form C Common J8-9 AC inhibit NO Form C NO  J8-10 ACinhibit NC Form C NC

Furthermore, the controller 500 includes a plurality of alarm outputports 575 each through an isolated Form C relay contact to couple withthe microprocessor 501. In one embodiment, the controller 500 is fittedwith five isolated Form C relay contact alarm outputs. The common ofeach of the alarm outputs is connected to a single point. The Form C(normally open) NO contact and (normally closed) NC contact of eachalarm relay coil are available for connection to a correspondingexternal device. Each relay coil is characterized by its capability ofswitching power up to 500 mA at 30V DC. In a specific embodiment, thealarm output ports 575 include functions of a general alarm output, asmoke alarm output, a hydrogen alarm output, an over-temperature alarmoutput, and a filter alarm output.

The general alarm output is triggered to indicate a blower failure (forexample, a blower has stopped or failed to reach a predefined percentageof its target speed) and a thermistor failure (when thermistor has openor short circuit), or a DC supply failure (when DC supply of the systemhas dropped below a predefined voltage). The relay coil associated withthe general alarm output is directly controlled from the microprocessor501 and is typically energized in the no-alarm condition so that analarm (associated with one of above three failures) output will be givenin the event of a total power failure to the controller PCB or a failurein the controller itself.

The smoke alarm output provides an isolated output depending on a smokealarm input signal from the smoke sensor connected to the microprocessor501. In one embodiment, the relay coil associated with the smoke alarmoutput is energized during alarm condition, but open in normalcondition.

The hydrogen alarm output provides an isolated output depending on ahydrogen alarm input signal from the hydrogen sensor connected to themicroprocessor 501. In one embodiment, the relay coil of the hydrogenalarm output is energized during alarm condition, but open in normalcondition.

The over-temperature alarm output provides an isolated output dependingon a temperature measured inside the shelter and a set point defined inthe functionality specification of the microprocessor 501. In oneembodiment, the relay coil of the over-temperature alarm output isenergized during alarm condition, but open in normal condition.

The filter alarm output provides an isolated output depending on aninput signal from a pressure switch 580 connected to the microprocessor501 for detecting if a filter arrangement associated with the blowers ofthe direct air cooling system is normal or abnormal. In one embodiment,the relay coil of the filter alarm output is energized during alarmcondition, but open in normal condition.

In a specific embodiment, the relay contact alarm outputs are interfacedwith the microprocessor 501 via a 12 way connector. For example, theconnector, namely J9, can be a Molex 12 way KK type 2.54 mm pitch headerwith friction lock connector (Molex Part No. 22-23-2121). Table 5 showsan exemplary connector pinout.

TABLE 5 Connector Ref Function Signal type J9-1 Alarm Common CommonSignal J9-2 Smoke Alarm Normally Open Contact J9-3 Smoke Alarm NormallyClose Contact J9-4 Hydrogen Alarm Normally Open Contact J9-5 HydrogenAlarm Normally Close Contact J9-6 Over Temp Alarm Normally Open ContactJ9-7 Over Temp Alarm Normally Close Contact J9-8 General Alarm NormallyClose Contact J9-9 General Alarm Normally Open Contact  J9-10 FilterAlarm Normally Open Contact  J9-11 Filter Alarm Normally Close Contact J9-12 Alarm Common Common Signal

Furthermore, the controller 500 is configured to receive an input from apressure switch 580 which is used monitor the pressure drop across thefilter to detect if the filter is clogged. As mentioned earlier, theinput signal from the pressure switch 580 is used to directly drive thefilter alarm relay and a LED for indicating filter alarm (to bedescribed later). The pressure switch 580 is driven by the on-board +5VDC supply 530. The interface between the microprocessor 501 and thepressure switch 580 is realized by a connector, namely J10. For example,a 2 way Molex KK type 2.54 mm pitch header with friction lock connectorcan be used (Molex Part No. 22-23-2021). Table 6 shows a pinout of theconnector.

TABLE 6 Connector Ref Function Signal type J10-1 Signal return Alarmsignal J10-2 Signal out Logic +5 V

Moreover, the controller 500 includes an on-board programming/test port590 and a communications port 595 associated with the microprocessor501. In one embodiment, the on-board programming/test port 590 is an InCircuit Serial Programming (ICSP) port which allows the flash memory inthe microprocessor 501 to be programmed or reprogrammed after thecontroller 500 has been assembled. The capability of reprogramming withan appropriate programmer facilitates the production programming of themicroprocessor 501 and also facilitates update of the program at a laterdate when necessary. This ICSP port 590 also is used for easy access tothe +5V DC supply 530 and 10.5V DC supply for production testing (butnot using ICSP). The interface between the on-board programming/testport 590 and the microprocessor 501 can be established via a 6 wayconnector, namely J11. For example, the connector can be a Molex KK type2.54 mm pitch header friction lock connector (Molex Part No.22-23-2061). Table 7 shows an exemplary connector pinout.

TABLE 7 Connector Ref Function Signal type J11-1 MCLR Master Clear J11-2Logic +Ve supply Logic 5 V Supply J11-3 Logic 0 V Logic 0 V Return J11-4PGC Program Clock J11-5 PGD Program Data J11-6 +10.5 V Supply 10.5 VSupply (for production test)

In another embodiment, the communications port 595 allows the controller500 to be connected via an adaptor to the RS232 type port or USB typeport of a personal computer. The communications port 595 is typicallyused for production testing of the system which is managed by thecontroller 500. The communications port 595 also can be set to broadcastperformance and status information during normal operation and can beused for performance analysis. The interface to the system through thecommunications port 595 can be established via a connector, namely J12.For example, the connector J12 can be a 3 way Molex KK type 2.54 mmpitch friction lock header connector (Molex Part No. 22-23-2031). Table8 shows an exemplary pinout for this connector.

TABLE 8 Connector Ref Function Signal type J12-1 TX Data Out J12-2 RXData In J12-3 Logic 0 V Logic Return

In a specific embodiment, the controller 500 also includes a pluralityof LED displays 577 coupled with the microprocessor 501. These LEDdisplays 577 are triggered by the plurality of relay contact alarmoutputs 575 to show different colored light. In one example, thecontroller 500 is fitted with seven 5 mm diameter round LED's which willbe visible through an aperture on the front of the fan tray's sheetmetal structure (e.g., blower subsystem 300 in FIG. 3B). In oneimplementation, these LEDs are mounted on the PCB of the controller 500.FIG. 5B shows three-angle views of the controller built on a PC boardaccording to an embodiment of the present invention. Of course, therecan be many variations, alternatives, and modifications in terms of thelayout of various controller components. This diagram is merely anillustration and should not limit the scope of the claims herein. Forexample, the controller 120 installed in the direct air cooling system100 shown in FIG. 1 or 300 shown in FIG. 3B is the same as thecontroller 500 described in above paragraphs. As shown, the controller500 is built on a printed circuit board (PCB) wherein some input/outputinterface devices are marked. For example, the input/output interfacedevices includes the connectors J1 through J12 and several LEDs (LED1through LED7). In particular, these LED's include the followingfunctions. LED1 is a status LED with bi-color RED/GREEN display linkedwith the general alarm relay. Green color is indicated when the directair cooling system us powered up and operating normally. Red colorindicator can further include continuous red light and flashing redlight for different alarm events with different priorities. LED2 is afilter alarm LED which shows single color RED only in the event of analarm. LED3 is over-temperature LED used for indicating theover-temperature alarm. LED4 and LED5 are respective smoke alarm LED andhydrogen alarm LED. Each of them is a single color LED normally off andin red light when alarming. LED6 is an AC inhibit LED used forindicating an inhibited A/C system with AMBER light but off when the A/Csystem is not inhibited or enabled. LED7 is an AC power fail alarm LEDshowing single RED color in the event of an alarm but off during normaloperation.

Alternatively, Embodiments of the present invention disclose a methodfor providing direct air cooling of electrical equipment operated withinoutdoor shelters supplemental to an existing air conditioning (A/C)system. In one embodiment, a simplified flow chart of the control methodis illustrated in FIGS. 6A and 6B for providing a controlled thermalmanagement for an outdoor shelter with the existing A/C system. Thisdiagram is merely an illustration and should not limit the scope of theclaims herein. One of skilled in the art should recognize manyalternatives, variations, and modifications. As shown, a method 600includes following processes:

Process 610: Providing a cooling system to a shelter with an A/C system,the cooling system comprising one or more blowers, a damper, and acontroller;

Process 615: Activating the controller operated from a DC supply;

Process 620: Receiving information associated with an interiortemperature and an exterior temperature;

Process 625: Monitoring information associated with a general alarm anda plurality of specific alarms;

Process 630: Processing information associated with the exteriortemperature and information associated with the general alarm and theplurality of specific alarms;

Process 640: Determining whether a general alarm is triggered, or one ormore specific alarms are triggered, or exterior temperature is greaterthan a predetermined value;

Process 645: If none of above occurs, processing information associatedwith the interior temperature;

Process 650: Determining whether a first criterion, or a secondcriterion, or a third criterion associated with the interior temperatureis satisfied;

Process 660: If the first criterion is satisfied, inhibiting the A/Csystem; then

Process 662: Operating the one or more blowers at a rotation speeddepending on the interior temperature; then

Process 664: Closing/Opening the damper as the rotation speed of one ormore blowers is/isn't zero;

Process 670: If the second criterion is satisfied, activating the A/Csystem in cooling mode; then

Process 672: Stopping the one or more blowers;

Process 680: If the third criterion is satisfied, activating the A/Csystem in heating mode; then

Process 682: Stopping the one or more blowers;

Subsequently, the method 600 requires to perform, after each of theProcess 672 and Process 682, the Process 664, followed by rerouted backto the Process 625 again in a closed loop.

The above sequence of processes provides a method according to anembodiment of the present invention. Other alternatives can also beprovided where processes are added, one or more processes are removed,or one or more processes are provided in a different sequence withoutdeparting from the scope of the claims herein.

In one example, the cooling system used in the method 600 is the same asthe direct air cooling system 100 shown in FIG. 1 and 300 shown in FIGS.3A and 3B. Following the method 600, the cooling system is provided formounting to a shelter at the Process 610. The cooling system includesone or more blowers configured to be mounted on an interior region of anshelter door, a filter arrangement configured to be mounted at an airinlet of the one or more blowers, and a damper arrangement configured tobe mounted else where at an air exhaust region of the shelter. Thecooling system further includes a controller. In one implementation, thecontroller is a microprocessor based controller operated from a DCsupply. The microprocessor features at least a first analog input, asecond analog input, a plurality of alarm inputs, one or more firstcontrol outputs, a second control output, and a third control output. Inparticular, the controller is the same controller 500 includingmicroprocessor 501 shown in FIGS. 5A and 5B.

The method 600 further includes a process of activating the controllerby starting up DC power from the DC supply (Process 615) to make themicroprocessor ready for executing preprogrammed control routines. Inaddition, the activation process involves an activation of a generalalarm relay coil and activations of a plurality of sensing devicesassociated with the controller. For example, a general alarm relay coilis activated and a two-color LED indicates green during a start upperiod (approximate 5 seconds). Among the plurality of sensing devices,a first thermistor and a second thermistor are activated for temperaturemeasurements. Other sensing devices includes a smoke sensor, a hydrogensensor, a pressure switch, one or more AC power monitoring modules, DCvoltage monitor, and the like.

Subsequently, the controller starts working with the activated pluralityof sensing devices. In particular, at the Process 620, themicroprocessor is receiving information associated with an interiortemperature and from the first analog input and information associatedwith an exterior temperature from the second analog input. In oneimplementation, the first analog input is a port called Input Temp 1connected to the microprocessor for delivering information associatedwith the interior temperature for the controller. Similarly, the secondanalog input is a port called Input Temp 2 connected to themicroprocessor for delivering information associated with the exteriortemperature for the controller. This process, in one implementation, isto start executing a closed-loop PWM control routine for the coolingsystem. In particular, the microprocessor, in response to at least thereceived information associated with the interior and exteriortemperatures, should generate adequate control signals for controllingthe speed of the one or more blowers. At the process 625, the controlleralso monitors information associated with the general alarm and aplurality of specific alarms received through the plurality of alarminputs. In one implementation, the microprocessor is able to adjust thecontrol signals based on received information associated with variousalarms indicating abnormal operational status of the cooling system.

At the Process 630 following the previous Processes 620 and 625, themicroprocessor firstly carries out a step for processing the receivedinformation associated with the exterior temperature and informationassociated with the general alarm and the plurality of specific alarms.In one embodiment, the cooling system sets to prioritize certainoperational and environmental conditions to generate adequate controlsignals. For example, a general alarm involving a blower failure, orthermistor failure, or DC supply fault, has high priority and needs tobe cleared first before performing rest operations. In certainexceptional case, during the starting up period, if the interiortemperature is such that the one or more blowers would normally bestopped, the one or more blowers will start up and run during the startup period to allow installation engineers to establish that the bloweris working normally. There is about 30 seconds delay to trigger generalalarm to prevent the controller from issuing alarms during the blowerstarting up period. After the start up period they will be turned off orwork to follow preprogrammed control routines. Additionally, somespecific alarms including smoke alarm and hydrogen alarm and theshelter's exterior temperature are determining factors on how thevarious control signals are formulated for controlling the coolingsystem. More details about the control method at various environmentaland operational conditions can be found below.

Based on the Process 630, the microprocessor is able to determine (atthe Process 635) whether the exterior temperature is lower than apredetermined value, or whether a general alarm or one or more specificalarms is triggered.

In case that a negative result is obtained at the Process 640, then themicroprocessor is to execute the next Process 645 for processinginformation associated with the interior temperature. Based on thisprocess, the microprocessor is able to determine (at the Process 650)whether one of the three criteria associated with the interiortemperature is satisfied. The three criteria simply corresponds to threepredetermined temperature ranges. If the interior temperature measuredby the first thermistor, determined by the microprocessor, falls intoone particular range, a particular criterion is satisfied. Accordinglybased on the programmed routine designed for the particular temperature,the controller generates adequate control signals to inhibit orre-activate the A/C system, to control a speed of each blower, and toopen/close the damper whenever the speed of each blower isn't/is zero.

In an event when the first criterion is satisfied, Process 660 will beexecuted. In one embodiment, the first criterion is defined as limitingthe interior temperature within a temperature window between a lowertemperature limit and a higher temperature limit. For example, if theinterior temperature is within a range of 0 Deg C. to 38 Deg C., thefirst criterion is satisfied. At Process 660 the microprocessor providesa control signal to inhibit the operation of the A/C system in thiscondition. Then (or essentially at the same time), Process 662 isexecuted to provide one or more control signals respectively to controlspeed of the blowers. Specific speed control depends on a specific valueof the interior temperature detected by the first thermistor which canbe installed near the one or more blowers at the interior side of theshelter. Process 664 (also can occur at substantially the same time) isexecuted to open the damper when the one or more blowers are blowing airinto the shelter while to close the damper when the one or more blowersare stopped (for any reason).

In one example, as the interior temperature is below 7 Deg C., allblowers will be turned off. If the interior temperature is rising (asthe electrical equipment in operation gradually heats up the shelter) to10 Deg C., the controller may decide to start turn the blowers on at aspeed of a certain speed, for example, about 1080 rpm. As the interiortemperature further increases above 10 Deg C., the average speed of theblowers will increase linearly to reach a higher speed, for example, upto about 3000 rpm, at about 35 Deg C. In one embodiment, at temperatureabove 35 Deg C. but still below the higher temperature limit for thefirst criterion, the blowers will operate at the full speed of 3000 rpmunless stopped by other conditions including unsatisfied first criterionand some alarming situations.

If the interior temperature increases (as the electrical equipment keepsits operation) above the higher temperature limit, for example 39 DegC., the second criterion becomes true. The Process 670 would betriggered in this condition. In particular, assuming no AC power supplyalarm input is received, the controller would providing a control signalto remove the inhibit of the A/C system to enable it to take over thecooling of the shelter. In other words, Process 672 is executed at asubstantially same time to stop the blowers. In fact, this is thecondition that the shelter is cooled under conventional way. However, ifthe interior temperature measured by the first thermistor drops from atemperature above the higher temperature limit to a temperature belowthat limit, for example 35 Deg C. or lower, then the controller willsend a control signal to inhibit the A/C system again and reestablishdirect air cooling by turning on the blowers at the proper speeddepending on the interior temperature.

If the interior temperature is below the lower temperature limit set forthe first criterion, the third criterion is satisfied. In thiscondition, the Process 680 is triggered. At this process the controlleris providing a control signal to remove the inhibit of the A/C system toallow it to operate in its heating mode to heat up the shelter.Accordingly, Process 682 is executed to stop the blowers. Usually, thisoccurs during a cold soak recovery process after an extended powerfailure at low temperature environment. However, it will disable the A/Csystem again once the interior temperature is above certain value above0 Deg C., for example 5 Deg C.

In either situation above, the damper arrangement associated with thedirect air cooling system is controlled in response to the operationstatus of the blowers. In one embodiment, whenever, the blower is turnedon, the damper arrangement will be instructed to open by a controlsignal sent by the controller. Whenever, the blower stops, the damperarrangement will be instructed to close by another control signal sentby the controller. In another embodiment, some events associated withon/off status of the blowers are related to one or more alarming events.

Referring back to FIG. 6, in case that the controller receives apositive result at the Process 640, i.e., either a general alarm istriggered, or one or more specific alarms is received by themicroprocessor, or simply the exterior temperature measured by thesecond thermistor is greater than a predetermined value, the method 600will move on to perform one of following processes: Process 700 through1100, depending on the specific conditions. FIG. 7 is a simplified flowchart showing a method for providing controlled cooling for an outdoorshelter according to an alternative embodiment of the present invention.In this specific condition, at the process 640A one specific alarm, asmoke alarm, is triggered (for example in case of fire). Then, themicroprocessor generates one or more control signals to turn offcorresponding blowers (Process 710) and close the exhaust damper(Process 720) to minimize the air supply (for the fire). In oneembodiment, the microprocessor also energizes a contact alarm relay coilassociated with the smoke alarm to generate a smoke alarm output signalwhich illuminates a LED in red color. Once the smoke alarm returns tonormal the controller will return to normal operation (i.e., the processflow would be led back to the Process 620 and on).

FIG. 8 is another simplified flow chart showing a method for providingcontrolled cooling for an outdoor shelter according to anotheralternative embodiment of the present invention. In the situation ofanother specific alarm, a hydrogen alarm, is received by themicroprocessor (Process 640B), one or more control signals will be sentto the blowers to speed them up (Process 810) to drive the hydrogen outof the shelter. In one example, the blowers will be on at full speed,for example about 3000 rpm. At the same time, the exhaust damper will bekept at an open state (Process 820) (irrespective of the temperature orany other control parameter) to vent the shelter. In one embodiment, themicroprocessor also energizes the contact relay coil associated with thehydrogen alarm and generate a hydrogen alarm output signal to illuminatea corresponding LED in red color.

FIG. 9 is another simplified flow chart showing a method for providingcontrolled cooling for an outdoor shelter according to anotheralternative embodiment of the present invention. In this situationanother specific alarm, an AC power fail alarm, is received by themicroprocessor (Process 640C). Usually, two redundant AC powermonitoring inputs are installed in the cooling system. If the controllerdetects an AC power fail on both the AC power monitoring inputs, it willoperate the blowers (or turn them on if they have been off) (Process910) at any temperature condition. At the same time, the damper shouldbe at an open state (Process 920) and an AC power fail alarm LED will beilluminated in red color.

FIG. 10 is yet another simplified flow chart showing a method forproviding controlled cooling for an outdoor shelter according to anotheralternative embodiment of the present invention. This is a situationthat the microprocessor receives an Input Temp 2 signal indicating thatthe exterior temperature is greater than a predetermined value (Process640D). In one example, the predetermined temperature value is 27 Deg C.for outdoor telecom shelters. Thus the controller will stop the blowers(Process 1010) and enable the A/C system (Process 1020) to cool theshelter until the exterior temperature cools down. Of course, the damperwill be kept at a closed state (Process 1030) during that period whenthe conventional A/C system is running. If the exterior temperaturedrops below the predetermined value, for example at 26 Deg C. or lower,the direct air cooling system will again replace the A/C system toprovide cooling for the shelter.

FIG. 11 is still yet another simplified flow chart showing a method forproviding controlled cooling for an outdoor shelter according to anotheralternative embodiment of the present invention. At Process 640E, ageneral alarm is triggered. In one embodiment, the general alarmincludes a blower fail alarm. If the speed of any blower drops below 70%of the speed of the other blowers then a general alarm will be triggeredby de-energizing the general alarm relay and a corresponding generalalarm LED will be changed to continuous red color. The controller willturn off all blowers (Process 1110) and also remove the inhibit of theA/C system to allow it to take over the cooling of the shelter (Process1120) unless there is also an AC power fault in which case thecontroller will operate the available blowers at maximum availablespeed. In one embodiment, the controller may notify the end user or aremote manager to send a technician to repair the blower that is introuble.

In another embodiment, the general alarm includes a thermistor failalarm. In particular, if the thermistor connected to either first analoginput or the second analog input is detected as either being open orshort circuited then a general alarm is triggered by de-energizing thegeneral alarm relay coil. Correspondingly in one implementation, thegeneral alarm LED is changing color to flashing red color. In this case,the controller will also remove the inhibit to the A/C system to allowit to take over the cooling of the shelter unless there is also an ACpower failure. If there is an AC power failure, i.e., the AC power failalarm has been triggered, the DC powered controller will keep onoperating the one or more blowers at full speed to draw cool air fromexterior into the shelter.

In yet another embodiment, the general alarm also includes a DC supplyfail alarm. The controller will monitor the DC supply voltage to thedirect air cooling system and has been programmed to take action atdifferent supply voltage. In one example, if the DC supply to thecontroller drops below 40V the controller will turn off all the blowersand close the damper to minimize the deep discharge of the batteries.The controller will also issue a general alarm in this condition. ThusProcess 1100 will be executed. The controller will resume normalfunction when the DC supply voltage to the controller reaches 42.5V.

In the event that there are multiple alarms priority of the generalalarms must be set. In one example, the controller will prioritize thealarm indications as follows. Priority 1 (highest priority): BlowerFail, indicating by a continuous RED LED; Priority 2: Thermistor Fail,indicating by a flashing RED LED. In one embodiment, there is an about30 seconds delay in blower alarms to prevent the controller from issuingalarms during the time that blowers are starting up.

There are some alarm situations that no immediate actions on either theoperation of blower/damper combination or inhibit/activation of A/Csystem. For example, if the controller detects an input alarm signalfrom a pressure sensor (or a pressure switch) the controller willenergize a filter alarm relay and illuminate the corresponding filteralarm LED in red color. The controller may also sent a message throughits communication port to remote manager to make a request of filterchange. Similarly, if the temperature detected by the thermistorconnected to Input Temp 1 reaches 44 Deg C. in reading, the controllerwill indicate an over-temperature alarm via an over-temperature alarmrelay and turn the corresponding LED to be illuminated RED. In thissituation, the cooling of the shelter has been taken over by the A/Csystem (assuming no AC power fault). However, certain message can besent to remote manager through the controller about the status of theshelter. The over-temperature alarm will be turned off if thetemperature drops to 42 Deg C., all other functions of the controllerwill remain as normal.

Many benefits can be achieved by embodiments of the present invention.Certain embodiments of the invention provide a simple addition of adirect air cooling system to existing telecommunications shelters bymounting the fan tray on the door of the shelter. The damper arrangementis conveniently mounted over one of the existing cable ducts in order toallow the field upgrade of the shelter. This structural design of thedirect air cooling system keeps the structural integrity of the existingtelecom shelter while providing a minimally invasive rework event. Someembodiments of the present invention utilizing the direct air cooling toprovide a supplemental thermal management with significant amount ofenergy saving and reduce overall system operating cost. Because forquite portion of time period, the operation of existing A/C systemassociated with the shelter are inhibited and the shelter is cooled bythe direct air cooling system based on embodiments of the presentinvention. In a specific embodiment, in the event of a power failure,the direct air cooling system can continue to operate normally from thebattery back up allowing the entire shelter to operate for as long asthere is power in the battery. Comparing to conventional shelter withA/C system only, the operation of the equipment within the shelter mayquickly become over-heated since no alternate cooling is provided.

It is also understood that the examples and embodiments described hereinare for illustrative purposes only and that various modifications orchanges in light thereof will be suggested to persons skilled in the artand are to be included within the spirit and purview of this applicationand scope of the applied claims.

1. A system for providing alternative cooling, in addition to an airconditioning (A/C) system, to a cabinet housing electrical equipment,the system comprising: a blower subsystem including one or more blowersfor drawing air from outside of the cabinet into the cabinet, the blowersubsystem comprising a bank of blower units and a path of airflow fromoutside of the cabinet into the cabinet that is absent an evaporatorelement of an A/C unit; a damper subsystem including a louverarrangement for controlling air exhaust; a controller operated from a DCsupply, the controller including a microprocessor having at least afirst analog input, a second analog input, a plurality of alarm inputs,one or more first control outputs, a second control output, and a thirdcontrol output; wherein: the first analog input connects to a firstthermistor to measure a first temperature inside the cabinet; the secondanalog input connects to a second thermistor to measure a secondtemperature outside the cabinet; the third control output connects tothe A/C system for inhibiting or re- activating the A/C system based onat least the first temperature and the second temperature, the one ormore first control outputs connect to the blower subsystem forrespectively operating the one or more blowers based on at least thefirst temperature when the A/C system is inhibited or stopped for anyreason; the second control output connects to the damper subsystem foropening/closing the louver arrangement when the one or more blowers areoperating/stopped.
 2. The system of claim 1 wherein the one or moreblowers comprise a two-channel configuration each channel having twoblowers, each blower being subjected a closed-loop pulse width modulated(PWM) speed control by modulating voltage from the DC supply.
 3. Thesystem of claim 1 wherein the plurality of alarm inputs are respectivelyconnected to a plurality of sensing devices to monitor environmentconditions and operation status of the electrical equipment within thecabinet.
 4. The system of claim 3 wherein the plurality of sensingdevices include a smoke sensor for generating a smoke alarm input signalto the controller when alarming, the smoke alarm input signal causingthe controller to respectively stop the one or more blowers through theone or more first control outputs.
 5. The system of claim 3 wherein theplurality of sensing devices further include a hydrogen sensor forgenerating a hydrogen alarm input signal to the controller whenalarming, the hydrogen alarm input signal causing the controller torespectively operate the one or more blowers at a predetermined maximumrotation speed.
 6. The system of claim 3 wherein the plurality ofsensing devices further include at least one AC power monitoring modulefor generating an AC fail alarm input signal when detecting powerfailure of each A/C system unit, the AC fail alarm input signal causingthe controller to respectively turn on the one or more blowers at arotation speed depending on the first temperature.
 7. The system ofclaim 1 further comprises a filter arrangement disposed at an air inletregion of the blower subsystem and coupled to the microprocessor througha pressure switch, the filter arrangement being associated with a filteralarm input signal when a pressure drop across the filter arrangement isdetected to be greater than a predetermined value by the pressureswitch.
 8. The system of claim 1 wherein the microprocessor further hasa plurality of alarm outputs coupled with a plurality of alarm displaydevices.
 9. The system of claim 8 wherein each of the plurality of alarmoutputs includes an isolated Form C relay contacts having a common port,a normally open (NO) contact, and a normally closed (NC) contact. 10.The system of claim 9 wherein the plurality of alarm outputs include ageneral alarm relay normally energized to a corresponding NO contact andde-energized to a corresponding NC contact to output a general alarmoutput signal in an event of at least a failure of one blower or thefirst thermistor or the second thermistor or the DC supply.
 11. Thesystem of claim 10 wherein the plurality of alarm display devicescomprise a bi-color LED display in response to the general alarm outputsignal.
 12. The system of claim 9 wherein the plurality of alarm outputsfurther include a smoke alarm relay, a hydrogen alarm relay, anover-temperature alarm relay, and a filter alarm relay, each beingnormally energized to a corresponding NC contact and de-energized to acorresponding NO contact when alarming to output a specific alarm outputsignal.
 13. The system of claim 12 wherein the plurality of alarmdisplay devices further comprise a single-color LED display for each ofcorresponding specific alarm output signal.
 14. The system of claim 1wherein the controller further comprises an In Circuit SerialProgramming port allowing programming and reprogramming of amicroprocessor flash memory and production testing.
 15. The system ofclaim 1 wherein the controller further comprises a communications portallowing the controller being connected to a personal computer via anadaptor to RS232 port or USB port.
 16. The system of claim 1 wherein thecontroller further comprises an EMC filter between the DC power inputand rest portion of the controller.